This invention relates to filtering apparatus used to remove particulate and chemical contaminants from liquids, and in particular from hot cooking oils and fats used in deep fryers.
Deep fryers are used extensively to prepare certain foods such as French fried potatoes, fish and the like, in restaurants, drive-ins and other eating places. Such a fryer ususally includes a tank or container filled with cooking oil or fat which is heated to a temperature of approximately 375.degree.. The food to be fried is then immersed for a predetermined time in the hot oil or fat. Deep frying, however, causes fat to break down and food particles to burn, chemically forming acids and carbon particles which lend an undesirable taste and color to the food and often cling to it. Accordingly, cooking oils and fats lose their effectiveness as cooking mediums after relatively short periods of use. Even with regular straining, the cooking medium will still contain a large amount of burnt particles, chemical contaminants, and import objectionable odors and taste.
Therefore, it has become popular to pass or circulate hot cooking oils or fats through a filtration apparatus to attempt to remove these contaminants and odors. While various filtration apparatus have been devised to remove such contaminants, many of these devices are incorporated into the deep fryer itself and are prohibitive in cost for a small fast food operation having several deep fryers. Other devices are relatively complex in construction and operation, using differential pressures, centrifugal force, or carbon, micron or graded filters to remove contaminants. Other filter apparatus use filter bags or screens which are easily clogged, require constant cleaning or disposal, and are not effective to remove all the contaminants and odors. Many prior filtration apparatus have also required constant manual cleaning of the filter, involving additional time and expense.